Chapter

Assessment instruments

Michael Terman, Janet B. W. Williams and Thomas M. White

in Seasonal Affective Disorder

Second edition

Published on behalf of Oxford University Press

Published in print October 2009 | ISBN: 9780199544288
Published online February 2013 | e-ISBN: 9780191754593 | DOI: http://dx.doi.org/10.1093/med/9780199544288.003.0018
Assessment instruments

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Research on seasonal affective disorder (SAD) has been prolific over the past 30 years, benefited by a community effort using common protocols and measures. This has enabled direct comparisons of prevalence estimates and clinical trials worldwide, cross-center pooling of early light therapy data (Terman et al. 1989) and meta-analyses of efficacy (Thompson et al. 1999; Golden et al. 2005). Specialized instruments have been devised to assess seasonal symptom variation in patients and the general population, diagnose the disorder, and measure symptom severity and response to treatment.

The use of structured interview guides reduces within- and between-center variance of clinical data as well as inter-rater variance, and thus enhances the coherence and convergence of results. Structured interviews designed to enhance the use of depression rating scales antedated SAD research (Williams 1988) and have been applied to diagnostic assessments for a wide scope of DSM-III and DSM-IV disorders (First et al. 1995). Related instruments have been tailored specifically for SAD. Raters read aloud a series of standardized, symptom-specific stem questions, and elaborate with designated probes if the patient's initial response is not clear-cut. Each response is scaled according to a series of ordinal, categorical anchor points that reflect symptom severity and frequency. The time frame may be retrospective or current (i.e., focused on the past week). Total scores provide a global measure of clinical state and change in state with treatment or seasons of the year, while item analysis allows documentation of symptom-specific effects. Structured interviews provide the additional advantage of feasible administration by raters who lack advanced clinical training and credentials, e.g., research assistants who would be unqualified independently to assess clinical states. Training requires dual ratings with a clinician, or another established interviewer, until inter-rater reliability converges to within a couple of points in the total score.

This chapter reviews a set of well-established and recent instruments for SAD research in four general formats: questionnaires, structured interviews for administration by a clinician or trained research assistant, paper-and-pencil versions of structured interviews in a self-rating format, and online instruments with automatic scoring. Although the latter formats remove the clinical observer from the assessment, their reliability compared to interviewer ratings can be sufficiently high to serve as a measure in outpatient field studies, as a check against interview results, and for patient self-assessment.

Our survey is divided into two sections: questionnaire instruments that infer the presence of SAD and are designed to measure seasonal variation, and structured instruments (in both interviewer and self-rating formats) designed for formal diagnosis and the scaling of syndromal severity.

Chapter.  4209 words.  Illustrated.

Subjects: Psychiatry

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